Key Engineering Materials
Vols. 342-343
Vols. 342-343
Key Engineering Materials
Vols. 340-341
Vols. 340-341
Key Engineering Materials
Vol. 339
Vol. 339
Key Engineering Materials
Vols. 336-338
Vols. 336-338
Key Engineering Materials
Vols. 334-335
Vols. 334-335
Key Engineering Materials
Vol. 333
Vol. 333
Key Engineering Materials
Vols. 330-332
Vols. 330-332
Key Engineering Materials
Vol. 329
Vol. 329
Key Engineering Materials
Vols. 326-328
Vols. 326-328
Key Engineering Materials
Vols. 324-325
Vols. 324-325
Key Engineering Materials
Vols. 321-323
Vols. 321-323
Key Engineering Materials
Vol. 320
Vol. 320
Key Engineering Materials
Vol. 319
Vol. 319
Key Engineering Materials Vols. 330-332
Paper Title Page
Abstract: Composites of calcinated bovine bone derived hydroxyapatite (BHA) doped 0.5 and 1 wt%
CaF2 were prepared by sintering. The production of BHA from natural sources is preferred due to
money and time saving reasons. Scanning electron microscopy (SEM) and X-ray diffraction analysis
together with measurements of density and compression strength were carried out in the produced
samples. The experimental results indicated that compression strength of the composites increase
when sintering temperature increases. The best compression strength was achieved after sintering at
1200°C for 0.5% CaF2 addition. The results are in agreement with densification measurements and
microstructure analysis. With regards to the amount of CaF2, the results indicate that small additions
of F, lower than 0.5%, can further improve the mechanical properties of HA.
43
Abstract: Composites of calcinated bovine bone derived hydroxyapatite (HA) with 0.5 and 1 wt%
Y2O3 were prepared by sintering. Money and time saving feature the production of HA from natural
sources. In this study, results of scanning electron microscopy (SEM) and X-ray diffraction analysis
aimed to interpret the results of measurements of densification, microhardness, and compression
strength of the produced composites. The best mechanical properties were achieved after sintering at
1200°C for compressive strength and 1300°C for microhardness. The results are in a fair agreement
with densification measurements and microstructure analysis.
47
Abstract: Biphasic α-tricalcium phosphate/hydroxyapatite (α-TCP/HA) calcium phosphate (BCP)
is prepared through a modified slip casting based method: α-TCP powders are dispersed in the HA
precursor solutions to form castable slurries, then the slurries are poured into round mold. After
curing, the slurries turn into cakes. Room temperature curing leads the cakes to contain α-TCP and
HA phases. Higher temperature heat treatment will result in the increase of HA content, while even
higher temperature will leads the cakes to be triphasic. Low temperature derived BCP have
particular microstructure with HA covers the surface of α-TCP powders, and these powders further
agglomerate into large blocks. After higher temperature treatment, β-TCP dominates the cake and
microporous structure is resulted.
51
Abstract: A simplified preparation method of silicon-substituted calcium phosphates with a very
high yield (close to 100%) has been elaborated, according to the principles of Green Chemistry. The
technique consists of mixing of crystals of calcium nitrate and ammonium dihydrogen phosphate in
the desired proportions, following by addition of the necessary amount of a silicon-containing
compound. The homogenous mixture is sintered between 900 and 1200°C. Either a siliconcontaining
hydroxyapatite (Si-HA) or a silicon-stabilized tricalcium phosphate (Si-αTCP) can be
synthesized, depending on the Ca/P, Ca/(P+Si) and Si/P molar ratios.
55
Abstract: Hydroxy carbonated apatite (HCA) powders were prepared by precipitation from a
modified SBF solution (5x M-SBF). The ionic concentrations were 5 times higher than in human
blood plasma with the exception of Mg2+ and HCO3
- concentrations that were reduced in order to
accelerate crystal growth. Spheroaggregates of HCA platelets with molar (Ca+Mg)/P ratios ranging
from 1.44 to 1.56 were obtained after precipitation at 50 °C. The crystallite size in c-direction was
approximately 20 nm and depending on the precipitation time a CO3
2- content of 1.8 to 5.2 wt.-%
was determined. Using this low temperature precipitation method, HCA powders with a high
specific surface area of 83 m2/g and a composition and crystallite size close to those of the mineral
phase of human bone were obtained.
59
Abstract: Merwinite powders were synthesized by a sol-gel process. The bioactivity in vitro of merwinite was
investigated by soaking the powders in simulated body fluid (SBF), the growth of hydroxyapatite(HAp) on the
surface of the powder was evaluated in various time. It was found that hydroxyapatite was formed after soaking
for 14 days. The results indicate that merwinite possessed apatite-formation ability might be a potential candidate
biomaterial for hard tissue repair.
67
Abstract: The response of osteoblast-like cells cultured on blasted and/or acid etching
surfaces and the influence of surface texture or microtopography on cell attachment, cell
proliferation, and the gene expression of the osteoblastic phenotype using ROS 17/2.8 cell
lines were evaluated. The blasted and/or acid etching surfaces were significantly rougher in
comparison to machined and etched surfaces (p < 0.05). On X-ray diffraction analysis,
titanium hydride (TiH2) was observed on the surface etched with a mixture of HCl-H2SO4
solution, whereas TiH2 was not observed on machined and blasted surfaces. After 24 h
incubation, most of the cells of all the groups had a flattened, polygonal shape and were fully
spread, exhibiting the onset of proliferation. The MTT assay showed a significant decrease on
the blasted surface compared to the machined surface at 7 day culture (p < 0.05). The
expression of osteopontin mRNA, α1 (I) collagen mRNA, and alkaline phosphatase mRNA
on rough surfaces was higher than on the machined surfaces, and was highest on the blasted
surface at day 7.
71
Abstract: The effect of anodic oxide films produced by β-glycerophosphate (β-GP) and calcium
acetate (CA) anodizing on osteoblast-like cell attachment and spreading were evaluated in this
study. Anodic oxide films were produced in different conditions: Group 1, 0.02 M β-GP and 0.2 M
CA; Group 2, 0.03 M β-GP and 0.2 M CA; Group 3, 0.03 M β-GP and 0.2 M CA. Anodic oxide
surface was significantly rougher in comparison to the control untreated titanium surfaces, and the
surface roughness and composition of phosphate and oxide increased as the concentration of β-GP
was increased. There was no significant difference in the cell viability when cells were cultured on
the control or anodized surface using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide
(MTT) assay. Scanning electron micrographs revealed more spread cells on the anodized surface
than on the smooth control surface. In conclusion, we suggested that the positive effects of anodized
surfaces produced by β-GP and CA on spreading of osteoblast-like cells may be the result of the
difference of surface roughness and amount of Ca and P in the oxide layer.
75
Abstract: Electrophoresis can transport ions more rapidly and directionally in a gel. The controlled
precipitation of calcium phosphates in an agarose gel was attempted by electrophoresis of calcium
and phosphate ions. Wells were prepared on an agarose gel. A CaCl2 solution was placed in wells
on the positive side and a Na2HPO4 solution in wells on the negative side. A potential of 100 V
was then applied. White precipitates appeared in the gel after 11 min. The white area initially
became larger and more intense with increasing time. However, after longer periods, the white area
decreased and became weaker, before disappearing after 45 min. Spinous precipitates with a
diameter of about 500 nm were obtained when the gels were collected after 20 min. The precipitates
were characterized as particles of calcium phosphate.
79