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  • 1
    Electronic Resource
    Electronic Resource
    Calculation of the deuterium electric field gradient in DF (1986)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 84 (1986), S. 5639-5644 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We report theoretical results of the electric field gradient at the position of the deuterium nucleus in the DF molecule. The purpose of the calculation is the evaluation of a correction term to the expectation value of the electric field gradient with respect to a linear combination of atomic orbitals-molecular orbital self-consistent field (LCAO-MO SCF) function proposed by Ransil. Our method is based on a variation-perturbation method that was proposed previously. The expectation value of q0D (el) is qD =−2.8964, the corrected value is qD (el)=−2.9056, and the experimental value is qD (exp)=−2.9241 (all values are expressed in terms of atomic units). The difference between our theoretical value and the experimental result is 0.6%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.450820
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  • 2
    Electronic Resource
    Electronic Resource
    Calculation of the vibrational dependence of the electric field gradient in HD (1988)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 88 (1988), S. 3159-3162 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We calculate the deuterium electric field gradient in the HD and D2 molecules at various internuclear separations by making use of a previously proposed variation–perturbation method. We calculate DEFG values at internuclear separations R=1.2, 1.3, 1.4, 1.5, and 1.6. We also calculate the average values for the vibrational ground state v=0 and for the vibrational states J=0, J=1, and J=2 of the HD and D2 molecules. The vibrational averaged DEFG value is very close to the equilibrium value at R=1.4 due to accidental cancellation of different contributions. The difference between our result and other theoretical values is about 2.5%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.453960
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  • 3
    Electronic Resource
    Electronic Resource
    Biocompatibility of Fluor-Hydroxyapatite Bioceramics (2005)
    Oxford, UK : Blackwell Science Inc
    Journal of the American Ceramic Society 88 (2005), S. 0 
    Details
    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: Fluoridated hydroxyapatite (FHA) powders were fabricated by a solid-state reaction, and their dense bodies were obtained by sintering at 1350°C. The biological performance of FHAs was evaluated and compared with that of pure hydroxyapatite (HA). The fluoridation of FHAs was confirmed by the changes in their lattice parameters. Human osteoblast-like cells attached and proliferated well on all of the FHAs, including pure FA. The proliferation and differentiation levels of the cells on FHAs were similar to those on pure HA. This finding suggests that the FHAs possess cell viability and activity comparable to pure HA, and thus are potentially applicable as hard tissue substitutes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1551-2916.2004.00172.x
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  • 4
    Electronic Resource
    Electronic Resource
    Sol–Gel Preparation and Properties of Fluoride-Substituted Hydroxyapatite Powders (2004)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of the American Ceramic Society 87 (2004), S. 0 
    Details
    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
    URL: http://dx.doi.org/10.1111/j.1151-2916.2004.tb06344.x
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  • 5
    Electronic Resource
    Electronic Resource
    Effect of Oxidation on Mechanical Properties of Fibrous Monolith Si3N4/BN at Elevated Temperatures in Air (2002)
    Westerville, Ohio : American Ceramics Society
    Journal of the American Ceramic Society 85 (2002), S. 0 
    Details
    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: The oxidation behavior and its effect on the mechanical properties of fibrous monolith Si3N4/BN after exposure to air at temperatures ranging from 1000° to 1400°C for up to 20 h were investigated. After exposure at 1000°C, only the BN cell boundary was oxidized, forming a B2O3 liquid phase. With increasing exposure temperature, the Si3N4 cells began to oxidize, forming crystalline Y2Si2O7, SiO2, and silicate glass. However, in this case, a weight loss was observed due to extensive vaporization of the B2O3 liquid. After exposure at 1400°C, large Y2Si2O7 crystals with a glassy phase formed near the BN cell boundaries. The oxidation behavior significantly affected the mechanical properties of the fibrous monolith. The flexural strength and work-of-fracture decreased with increasing exposure temperature, while the noncatastrophic failure was maintained.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1151-2916.2002.tb00597.x
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  • 6
    Electronic Resource
    Electronic Resource
    Mechanical Properties of Three-Layered Monolithic Silicon Nitride–Fibrous Silicon Nitride/Boron Nitride Monolith (2002)
    Westerville, Ohio : American Ceramics Society
    Journal of the American Ceramic Society 85 (2002), S. 0 
    Details
    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: A three-layered composite, composed of a strong outer layer (monolithic S3N4) and a tough inner layer (fibrous Si3N4/BN monolith), was fabricated by hot-pressing. For the inner layer, a Si3N4–polymer fiber made by extrusion was coated by dipping it into a 20 wt% BN-containing slurry. The three-layered composite exhibited excellent mechanical properties, including high strength, work of fracture, and crack resistance, because of the combination of a strong outer layer and a tough inner layer. In other words, the strong outer layer withheld the applied stress, while the tough inner layer promoted crack interactions through the weak BN cell boundaries. Also, the residual thermal stress on the surface due to the anisotropy in the coefficient of thermal expansion of BN affected a median/radial crack generation after indentation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1151-2916.2002.tb00538.x
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  • 7
    Electronic Resource
    Electronic Resource
    Improvement of Hydroxyapatite Sol–Gel Coating on Titanium with Ammonium Hydroxide Addition (2005)
    Oxford, UK : Blackwell Science Inc
    Journal of the American Ceramic Society 88 (2005), S. 0 
    Details
    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
    URL: http://dx.doi.org/10.1111/j.1551-2916.2004.00030.x
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  • 8
    Electronic Resource
    Electronic Resource
    Co-Firing of Spatially Varying Dielectric Ca–Mg–Silicate and Bi–Ba–Nd–Titanate Composite (2005)
    Oxford, UK : Blackwell Science Inc
    Journal of the American Ceramic Society 88 (2005), S. 0 
    Details
    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: A spatially variant dielectric Ca–Mg–silicate (CMS)/Bi–Ba–Nd–titania (BBNT) composite, in which periodic BBNT inclusions were embedded in the CMS matrix, was fabricated using the thermoplastic extrusion. The co-firing behavior of the composite was evaluated in terms of its shrinkage compatibility, thermoplastic compatibility, and chemical compatibility. The noticeable shrinkage mismatch between CMS and BBNT materials was observed. Such shrinkage mismatch strongly affected the interfacial bonding types of the composites. The good interfacial bonding was observed for the composite having BBNT inclusions in the CMS matrix; however, the interfacial cracking and matrix cracking for the opposite design (i.e., CMS inclusions in the BBNT matrix). In addition, the (Ca, Zn)-rich glassy phase in the CMS region migrated into the BBNT region, forming an interfacial reaction layer. The dielectric properties of the CMS, BBNT, and CMS–BBNT mixture were measured to evaluate the spatially variant dielectric CMS/BBNT composite as a novel dielectric substrate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1551-2916.2005.00498.x
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  • 9
    Electronic Resource
    Electronic Resource
    Pressureless Sintering and Mechanical and Biological Properties of Fluor-hydroxyapatite Composites with Zirconia (2003)
    Westerville, Ohio : American Ceramics Society
    Journal of the American Ceramic Society 86 (2003), S. 0 
    Details
    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: Fluor-hydroxyapatite (FHA) fabricated by a reaction between fluorapatite (FA) and hydroxyapatite (HA) was mixed with ZrO2 to produce FHA–ZrO2 composites. When the relative amount of FA to HA increased, the decomposition of the composite was decreased gradually because of the formation of thermally stable FHA solid solutions. With such suppression of decomposition, the FHA–ZrO2 composites retained fully densified bodies. As a result, significant enhancements in mechanical properties, such as hardness, flexural strength, and fracture toughness, were achieved as the relative amount of FA to HA increased. The highest values in strength and toughness were 220 MPa and 2.5 MPa·m1/2, respectively, with FHA–40 vol% ZrO2 composites. In vitro proliferation of osteoblast-like cells (MG63) on the composites showed behavior similar to that observed on pure HA and FHA. Alkaline phosphatase (ALP) activity of the growing cells (HOS) on the composites was slightly down-regulated compared with that on pure HA and FHA at prolonged periods.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1151-2916.2003.tb03602.x
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  • 10
    Electronic Resource
    Electronic Resource
    Reaction Sintering and Mechanical Properties of Hydroxyapatite–Zirconia Composites with Calcium Fluoride Additions (2002)
    Westerville, Ohio : American Ceramics Society
    Journal of the American Ceramic Society 85 (2002), S. 0 
    Details
    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: The effects of calcium fluoride (CaF2) additions on the densification and mechanical properties of hydroxyapatite–zirconia composites (HA–ZrO2) were investigated. When small amount of CaF2 was added, the density of the composites was markedly enhanced. The reactions of HA with CaF2, which led to the formation of fluorapatite (FA), were attributed to the observed improvements in densification. When HA–20-vol%-ZrO2 composites were sintered, with the addition of 5 vol% of CaF2, in air at 1300°C, the density of the specimen approached 98% of the theoretical value. The flexural strength and fracture toughness of the composites were also improved, as a result of the enhanced densification.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1151-2916.2002.tb00328.x
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