• 한국재료학회지
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• 제15권11호
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• pp.690-696
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• 2005

The ultrastructure ore of a nanostructured apatite film nucleated from solution was studied to gain insights into that of bone minerals which is the most important constituent to sustain the strength of bones. Needle-shaped apatite crystal plates with a bimodal size distribution $(\~100\;to\;\~1000 nm)$ were randomly distributed and they were found to grow parallel to the c-axis ([002]), driven by the reduction of surface energy. Between these randomly distributed needle-shaped apatite crystals which are parallel to the film, apatite crystals (20-40nm) with the normal of the grains quasi-perpendicular to the c-axis were observed. These observations suggest that the apatite film is the interwoven structure of apatite crystals with the c-axis parallel and quasi-perpendicular to the fan. In some regions, amorphous calcium phosphate, which is a precursor of apatite, was also observed. In the amorphous phase, small crystalline particle with the size of 2-3 nm were observed. These particles were quite similar, in size and shape, to those observed in the femoral trabecular bone, suggesting the nucleation of apatites by a biomimetic process in vitro is similar to that in vivo.

• 한국지하수토양환경학회지:지하수토양환경
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• 제20권2호
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• pp.32-40
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• 2015

Laboratory column experiments were conducted to evaluate the feasibility of injectable apatite method for the sequestration of Sr-90 in groundwater. The columns were tested to evaluate the rate of citrate biodegradation, the amounts of apatite formed, and the treatability of strontium by the sediment and apatite. The results showed the decreases in citrate, calcium, and phosphate concentrations and the increases in alkalinity and citrate degradation products (acetate and formate) in the columns, suggesting that the citrate degradation and formation of calcium phosphate are occurring. Although the calcium and phosphate were not completely consumed within the columns, some amounts of apatite were formed and it showed an ability to treat strontium in groundwater. This study provides a fundamental understanding of reaction mechanisms for the injectable apatite sequestration method for Sr-90 removal.

• 대한의용생체공학회:의공학회지
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• 제15권2호
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• pp.195-200
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• 1994

To develop an artificial bone substitute that is gradually degraded and replaced by the regenerated natural bone, the authors designed a composite that consists consisted of calcium phosphate and collagen according to the natural bone's main composition. The crystallinity of the synthesized apatite was shown to depend on the synthesis temperature. Carbonate apatite synthesized at $58{\circ}C$ demonstrated crystallinity very similar to that of the natural bone. By sintering the apatite over $700{\circ}C$ in vacuum, porous carbonate apatite could be obtained, and the pore extent was controllable according to the additive hydrogenperoxide volume.

• 대한금속재료학회지
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• 제48권6호
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• pp.575-580
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• 2010

Effects of the surface modification on the deposition behaviors of apatite crystals in Zr-1Nb plates were studied. Zr-1Nb alloy plates were polished with abrasive papers to have different roughness and some of them were treated in NaOH or coated with collagen before deposition of apatites in the simulated body fluid (SBF). The weight gain due to the deposition of apatite crystals increased as the surface roughness increased in Zr-1Nb. The size of granular apatite crystals were found to be smaller in Zr-1Nb roughened by $162{\mu}m$ abrasive paper than in Zr-1Nb roughened by $8.4{\mu}m$ paper, suggesting the nucleation rate increased with increase of surface roughness. After, 10 days immersion in a SBF, NaOH-treated Zr-1Nb was completely coated with apatite with the deposited apatite weight comparable to that in Ti-6Al-4V. The deposition rate of Zr-1Nb was not appreciably influenced by NaOH treatment unlike the significant influence of NaOHtreatment on the deposition rate of apatite in Ti-6Al-4V. One significant observation in this study is an appreciable increase of the apatite deposition rate after collagen coating both on Zr-1Nb and Ti-6Al-4V plate, which may be caused by the interaction between collagen and $Ca^{+2}$ ions.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2011년도 추계학술발표대회
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• pp.36.2-36.2
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• 2011

Titanium and its alloys have been widely used for orthopedic implants because of their good biocompatibility. We have previously shown that the crystalline titania layers formed on the surface of titanium metal via anodic oxidation can induce apatite formation in simulated body fluid, whereas amorphous titania layers do not possess apatite-forming ability. In this study, hot water and heat treatments were applied to transform the titania layers from an amorphous structure into a crystalline structure after titanium metal had been anodized in acetic acid solution. The apatite-forming ability of titania layers subjected to the above treatments in simulated body fluid was investigated. The XRD and SEM results indicated hot water and/or heat treatment could greatly transform the crystal structure of titania layers from an amorphous structure into anatase, or a mixture of anatase and rutile.The abundance of Ti-OH groups formed by hot water treatment could contribute to apatite formation on the surface of titanium metals, and subsequent heat treatment would enhance the bond strength between the apatite layers and the titanium substrates. Thus, bioactive titanium metals could be prepared via anodic oxidation and subsequent hot water and heat treatment that would be suitable for applications under load-bearing conditions.

• 한국지하수토양환경학회지:지하수토양환경
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• 제9권2호
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• pp.1-10
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• 2004

본 연구의 목적은 석회석 및 인회석을 이용한 실내실험을 실시하여 ARD 내의 비소저감 효율성을 평가하고 인회석 배수 체계를 설계하는 것이다. 실내실험 결과, pH, 비소저감율 및 석회석/인회석의 용해량은 유속에 반비례 하였으며 인회석은 유속 0.6 ml/min/kg에서 비소를 100％ 제거하였다. 인회석의 용해율은 석회석보다 10배 정도 높은 것으로 사료된다. 비소화합물은 비산염인회석 그리고/또는 칼슘비산염수화물의 형태인 것으로 추측된다. 실내실험에 근거하여 인회석 배수체계를 설계하였으며 그 결과는 다음과 같다; 1년 6개월 마다 인회석 62톤을 새로 충진시켜줘야 하며 침전물은 매 3개월 마다 침전조에서 제거해줘야 할 것이다.

• Restorative Dentistry and Endodontics
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• 제16권2호
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• pp.62-84
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• 1991

The purpose of this study was to evaluate the cytotoxicity of four root canal sealers(Tubliseal, AH26, Apatite Root Canal Sealer I, Apatite Root Canal Sealer II) in Vitro. The root canal sealers were mixed and filled in molds which were $14{\times}1.25mm$ in diameter, in height to use for cell counting and agar overlary method, and $7{\times}1.25mm$ for millipore filter method and set for 7 days to use for experiment. Silicone and copper plate were used for negative and positive control respectively. Using the culture of L929 fibroblast, total cell number and vital cell number were counted and the ratio of vital cell number to total cell number was calculated on 2 nd, 4 th, 6 th experimental day, and the change of cell membrane permeability was tested by agar overlay method, and the succinate dehydrogenase activity was tested by millipore filter method. The obtained results were as follows. 1. In ail experimental groups, the mitotic activity of fibroblast was reduced when compared with that of negative control group, so ail experimental groups showed cytotoxicity. Apatite Root Canal Sealer I group exhibited mild cytotoxicity, and Tubliseal, AH26, Apatite Root Cenal Sealer II groups exhibited severe cytotoxicity. 2. In the test of the change of cell membrane permeability by agar overlay method, all experimental groups showed cytotoxicity. AH26 group exhibited mild cytotoxicity, and Apatite Root Canal Sealer I group exhibited moderate cytotoxicity, and Tubliseal and Apatite Root Canal Sealer II group exhibited severe cytotoxicity. 3. In the test of SDH activity by millipore filter method, there was no cytotoxicity in Apatite Root Canal Sealer I and Apatite Root Canal Sealer II group, but Tubliseal and AH26 group showed mild cytotoxicity.

• The Korean Journal of Ceramics
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• 제5권3호
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• pp.265-269
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• 1999

Polyethylene was modified with silanol groups on its surface by photografting of vinyltrimethoxysilane in vapor phase by using benzophenon as a polymerization initiator and by hydrolyzing the methoxysilane groups into the silanol groups with HCI solution. The modified polyethylene formed a dense and homogeneous apatite layer on its surface in a solution with ion concentrations 1.5 times those of human blood plasma within 21 days. This kind of biomimetic process could provide techniques for fabricating apatite-polymer composites with three dimensional structure analogous to the natural bone.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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• pp.1089-1090
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• 2006

Biomimetic apatite deposition behaviors on Zr-1Nb and Ti-6Al-4V plate with various surface conditions were examined. Both alloys were polished with abrasive papers to have different roughness and some of them were treated in NaOH before exposition in simulated body fluid. NaOH treatment was found to enhance the deposition rate of apatite on Ti-6Al-4V significantly. On the other hand, the deposition rate of Zr-1Nb was not influenced by NaOH treatment. Without NaOH treatment, the polished Zr-1Nb with abrasive paper was found to induce more apatite nucleation than the polished Zr-6Al-4V.

• The Korean Journal of Ceramics
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• 제4권4호
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• pp.336-339
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• 1998

Bioactive titanium metal can be prepared by simple 5M-NaOH treatment and subsuquent heat treatment at $600^{\circ}C$ to form an amorphous sodium titanate on its surface. In the present study, mechanism of apatite formation on the titanium metal was investigated by examining its surface compositional and structural changes in a simulated body fluid. The apatite formation on the metal was found to proceed in the sequence of 1)$Na^+$ ion release from the sodium titanate to form hydrated titania abundant in Ti-OH groups, 2) early and selective binding of calcium ions with the Ti-OH groups to form a calcium titanate, and 3) late binding of phosphate ions to make apatite nucleation and growth. This indicates that Ti-OH groups do not directly induce the apatite nucleation, but via formation of a calcium titanate.