• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2005.10a
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• pp.103-104
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• 2005

• Proceedings of the Materials Research Society of Korea Conference
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• 2005.05a
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• pp.309-309
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• 2005

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.8 no.1
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• pp.169-178
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• 1998

The crystal phases precipitated in various compositions glass of CaO-$SiO_2-P_2O_5$ system, were identified by XRD. E composition (CaO 49.4, $SiO_2\;36.8,\;P_2O_5$ 8.8 wt%) glass in which both apatite(($Ca_{10}(PO_4)_6O$ and $\beta$-wollastonite($CaSiO_3$) crystals would precipitate by heating, was selected as an experimental composition to prepare the glass ceramics with high bending strength and good bioactivity to the living bone. Glass powders of E composition were unidirectionally crystallized at $1050^{\circ}$C in the temperature-gadient furnace and the resultant glass ceramics were characterized. Bending strength of the glass ceramics was also measured. To investigate the bond forming ability between the glass ceramics and living bone tissue, soaking test of glass ceramics in simulated body fluid was carried out. Densed glass ceramics composed of apatite and $\beta$-wollastonite crystal were prepared by unidirectional crystallization under the optimum conditions. (2 0 2) plane of $\beta$-wollastonite crystals tended to grow perpendicularly to the crystallization direction. Average bending strength of this glass ceramics was 186.9 MPa, higher than that of the glass ceramics prepared by isothermal (not directional) crystallization In soaking test, a thin layer of apatite crystallite was formed on surface of the glass ceramics in 3 days. Apatite crystals formed on the glass ceramics could be act a role to make the chemical bond between the glass ceramics and living bone tissue.

• Economic and Environmental Geology
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• v.34 no.6
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• pp.617-625
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• 2001

The Skaergaard intrusion is widely considered a type example of a strongly fractionated, layered intrusion that has undergone extensive in situ igneous differentiation. The Intrusion, therefore, should be a good locality for modeling trace element vriation in a closed system. Previous studios (Haskin and Haskin, 1968; Faster et al., 1974), however, have suggested thats the rare earth elements in whole rocks and mineeral separates from the Intrusion did not fellow the expected trend for closed system crystatllization. Trace element modeling using published distribution coefficients, modal abundances of the coexisting minerals, and the concentration of trace elements In whole rocks and mineral separates from the Skaergaard Intrusion, reveals that the rare earth elements were significantly Influenced by the crystallization of abundant apatite in the Layered Series suring the final stages of crystallization. The results of trace element modeling also suggcsts that apatite, which appears sporadically in the UBS, is not a primary liquidus phase in these samples as previously suggested (Naslund, 1984) but an interstitial phase that (lid not directly effect trace element abundances In the evolving magma As the Skaergaard magma coaled convection, or convected as small Isolated cells during the final stages of differentiation, an elebated $P_{H2O}$ Induced by accumulation of volatile elements near the roof of the magma chamber ingibited or delayed the precipitation of primary apatite in the UBS If the Skaergaard differentiation Is modeler assuming primary apatite crystallization In the upper par of the LS where abundant modal apatite is present, and only late stage crystallization of apatite In the UBS where apatite Is less abundant, rare earth elements abundances follow a closed system variation trend. These results rule but any differentiation model for the Skaergaard Intrusion that Includesvolumetrically significant injections or discharges of magma Into or out of the chamber during the final 20% of the crystallization history.

• Journal of Korean society of Dental Hygiene
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• v.8 no.1
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• pp.13-22
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• 2008

This study compared tooth's remineralization using enamel surface artificially demineralized with 0.1M lactate and HCL solution using Vicker's Hardness Number(VHN) to compare CPP-ACP and remineralization of nano-sized Carbonate Apatite's initial caries. Using pH circulation models divided into 0% nano-CA, 5% nano-CA, 10% nano-CA, 10% CPP-ACP and D.W. they were treated for 5 minutes, three times a day for 14 days to get the following results. 1. There were no significant differences among the initial surface hardness of samples demineralized surface of front tooth in 5 groups. and all 5 groups' surface hardness reduced significantly after demineralization of enamel. 2. When inquiring into hardness changes through pH circulation model, the highest hardness change was in 5% nano-CA group. Also. 10% nano-CA and 10% CPP-ACP groups increased significantly. but there was no significant difference statistically. In generalizing the above experiment results, nano-sized Carbonate Apatite showed remineralization, and compared to 10% CPP-ACP group, 5% nano-CA had remineralization to artificial caries. thus implies that when we develop method to contact with tooth of nano-CA in the future, it is expected to gain synergy effect on function of saliva, a natural remineralization material.

• Journal of Korean Society of Water and Wastewater
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• v.27 no.6
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• pp.751-759
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• 2013

This study is carried out to get the basic design parameters for phospate removal facilites from wastewater by Tobermolite. The phosphate removal by the apatite formation on the surface was affected by several important factors, temperature, ions present in wastewater stream, contact time, recirculation rate, and etc. In case of the temperature, with the increase of temperature, the apatite formation was accelerated. When temperature increased from $15^{\circ}C$ to $35^{\circ}C$, removal efficiency of phosphate increased from 83 % to 93 %. An increase of calcium and fluoride ion content increase the apatite formation, however, bicarbonate and magnesium ion inhibited the crystallization of apatite. As expected, when the recirculation rate was increased from 1 Q to 3 Q, at EBCT (Empty Bed Contact Time) 60min enhanced removal efficiency was observed. The more the recirculation rate increased, the more the removal efficiency increased. According to the results of column experiment using an actual wastewater with low and high phosphate concentration (5 mg/L and 50 mg/L-P), the removal efficiency was 77 % at EBCT of 45 min, and 80 % at 60 min. It was suggested that optimum EBCT was 45 min.

• Journal of the Korean Ceramic Society
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• v.40 no.3
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• pp.255-261
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• 2003

Alumina glazed with a bioactive glass reacted in Simulated Body Fluids(SBF) to investigate the behavior of hydroxyapatite formation on the glass coat layer. Various crystalline phases were found depending on the firing temperatures when the bioactive glass coat was heat-treated. The glass coat was crystallized into ${\beta}$-wollastonite and apatite when fired at 1100$^{\circ}C$, and ${\alpha}$-wollastonite and apatite when fired at 1200$^{\circ}C$. Those samples reacted in SBF, and it is observed that hydroxyapatite developed on the surface of the crystallized glaze. Its formation was much easier in the sample with ${\alpha}$-wollastonite than with ${\beta}$-wollastonite. This is because that the ${\alpha}$-wollastonite dissolves more easily than ${\beta}$-wollastonite does in SBF.

• Journal of Biomedical Engineering Research
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• v.15 no.2
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• pp.189-194
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• 1994

Effects of ${AI_2O_3}/{P_2O_5}$ ratio on the crystallization of a series of glasses with the nominal composition of 41.4wt % $SiO_2$, 35.0wt % CaO, 20.6wt % (${P_2O_5}$+${AI_2O_3}$) and 3.0wt% MgO were investigated with DTA, XRD and SEM. The major crystalline phases are apatite and anorthite. The glass transition temperature ($T_g$) and the softening point ($T_s$) are shifted to the upper temperature by increasing $AI_2O_3$ content. The temperature of apatite crystallization ($T_{p1}$) is increased by $AI_2O_3$ content, but the tempera¬ture of anorthite crystallization ($T_{p2}$) is not affected significantly. With increased of $AI_2O_3$, the apatite crystallization is decreased, but anorthite crystallization is increased.

• Korean Journal of Metals and Materials
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• v.47 no.12
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• pp.881-886
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• 2009

Research into the replacement of injured systems and tissue in the human body is advancing rapidly. Recently, Ti-Ni shape memory alloys have shown excellent biofunctionality related to their shape memory effect and superelasticity. In this study, the effect of an acid or an alkali treatment on the bioactivity in 49Ti-Ni and 51.5Ti-48.5Ni alloys is investigated in an effort to utilize Ti-Ni alloy as a biomaterial. In addition, the biocompatibility in a SBF solution is assessed through in vitro testing. A porous surface was formed on the surface of both alloys after a chemical treatment. According to the in vitro test, apatite formed on the surfaces of both alloys. The forming rate of apatite in the Ti-rich alloy was faster that in the Ni-rich alloy. The formation of apatite provided proof of the bioactivity of the Ti-Ni alloy. A small quantity of Ni was eluted at the initial stage, whereas Ni was not found for 12 days in the Ti-rich alloy and for 8 days in the Ni-rich alloy. In the case of the treated 51.5Ti-Ni alloy, the shape memory property was worsened but the biocompatibility was improved.

• Biomaterials and Biomechanics in Bioengineering
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• v.1 no.1
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• pp.51-62
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• 2014

The purpose of this experiment was to evaluate the apatite-formation abilities of low-modulus Ti-7.5Mo substrates treated with NaOH aqueous solutions and subsequent ethyl alcohol aging before soaking them in simulated body fluid. Specimens of Ti-7.5Mo were initially treated with 5 M NaOH at $60^{\circ}C$ for 24 h, resulting in the formation of a porous network structure composed of sodium hydrogen titanate. Afterwards, the specimens were aged in ethyl alcohol at $60^{\circ}C$ for 5 or 10 min, and subsequently immersed in simulated body fluid at $37^{\circ}C$ for 3, 7 and 14 days. Ethyl alcohol aging significantly increased the apatite-forming abilities of Ti-7.5Mo. The amount of apatite deposited on the Ti-7.5Mo after NaOH treatment and subsequent ethyl alcohol aging was much greater, especially after the Ti-7.5Mo specimens were aged for 5 min. Due to its excellent combination of bioactivity, low elastic modulus and low processing costs, the Ti-7.5Mo treated with NaOH aqueous solutions and subsequently aged in ethyl alcohol has promising heavy load-bearing applications.