• Journal of the Korean Crystal Growth and Crystal Technology
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• v.10 no.2
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• pp.171-176
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• 2000

The phosphatic calcium compounds such as calcium hydrogen phosphate, bone ash, hydroxyapatite and tricalcium phosphate were prepared using the high purity calcium hydroxide and calcium carbonate obtained from shell resources. Calcium hydrogen phosphate had been prepared using the high purity calcium hydroxide and phosphoric acid solution. Using the calcium hydrogen phosphate as a starting materials, bone ash have been prepared by solid state reaction method and hydroxyapatite could be obtained by hydrothermal treatment method, respectively. The tricalcium phosphate was prepared by the solid state reaction of a stoichiometic mixture of bone ash and high purity calcium carbonate. In this paper, the optimal preparation process and conditions of phosphatic calcium compounds were established.

• Applied Biological Chemistry
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• v.18 no.3
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• pp.145-166
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• 1975

The calcium balance study was carried out to determine the availability of calcium in different sources for chicks and laying hens. The sources of calcium were calcium carbonate (CC), dicalcium phosphate-dihydrate (DCPH), and dicalcium phosphate-anhydride (DCPA) for chicks and calcium carbonate (CC) and oyster shell (OS) for laying hens. The radioisotope dilution method was employed to measure the endogenous excreta calcium during the period of balance study following preliminary feeding. A. Experimental results with chicks: No significant difference was found among feed consumption of chicks fed diets containing different sources of calcium. Body weight gain of chicks was dependent upon the source of calcium. The gain decreased in the order of DCPH, DCPA and CC (P<0.01). The feed conversion efficiency in chicks fed DCPH was better than those in chicks fed CC or DCPA. The average tibia ash contents for chicks fed different sources of calcium were similar. The DCPH was superior to CC or DCPA regarding the calcium content in tibia ash. There were no significant differences among the average calcium contents in plasma trichloracetic acid filtrate in chicks irrespective of calcium sources. The mean apparent retention of calcium by chicks fed DCPH, CC and DCPA were 65.9, 64.0 and 59.9% respectively. The calcium to phosphorus ratios in tibia ash and plasma trichloracetic acid filtrate for chicks fed different sources of calcium were similar. The chicks fed DCPH showed the partition of endogenous excreta calcium in total excreta calcium as 35.6% which was higher than 31.0 or 31.4% for chicks fed CC or DCPA. The endogenous excreta calcium per day per chick in group fed DCPH, DCPA or CC were 17.2, 16.1 and 14.6mg respectively. The true retained calcium per day per chick in group fed DCPH were 109.9 mg which was higher than those observed with CC or DCPA group (P<0.01). The true retention of calcium by the birds fed diets containing DCPH, CC or DCPA were 78.1, 75.1 or 72.6% respectively. B. Experimental results with laying hens: The feed consumption, egg production and feed converion efficiency of laying hens fed diets containing different sources of calcium were similar. Calcium concentration in plasma trichloracetic acid filtrate in laying birds fed CC was equivalent to the value obtained by feeding OS. The apparent calcium retention by laying birds fed CC was 61.6% and it was significantly more than that of hens fed OS of 51.6% (P<0.05). The partition of endogenous excreta calcium in total excreta calcium of laying hens fed CC was 23.5% and this was higher than that of birds fed OS of 15.6%. The laying hens fed CC showed 310 mg of endogenous excreta calcium per day per bird while birds fed OS showed 261mg. The true retention of calcium by layers fed CC was 70.7% against 59.2% for birds fed OS (P<0.05).

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.11
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• pp.1237-1242
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• 2011

Calcium phosphates are very interesting materials for use as scaffolds for bone tissue engineering. These materials include hydroxyapatite (HA) and tricalcium phosphate (TCP), which are inorganic components of human bone tissue and are both biocompatible and osteoconductive. Although these materials have excellent properties for use as bone scaffolds, many researchers have used these materials as additives to synthetic polymer scaffolds for bone tissue regeneration, because they are difficult to manufacture three-dimensional (3D) scaffolds. In this study, we fabricated 3D calcium phosphate scaffolds with the desired inner and outer architectures using solid freeform fabrication technology. To fabricate the scaffold, the sintering behavior was evaluated for various sintering temperatures and slurry concentrations. After the fabrication of the calcium phosphate scaffolds, in-vitro cell proliferation and osteogenic differentiation tests were carried out.

• Progress in Medical Physics
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• v.15 no.4
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• pp.220-227
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• 2004

In N-type $Ca^{2＋}$ channels, the mechanism of inactivation - decline of inward current during a depolarizing voltage step- is still controversial between voltage-dependent inactivation and $Ca^{2＋}$ -dependent inactivation. In the previous paper we demonstrated that fast component of inactivation of N-type calcium channels does not involve classic $Ca^{2＋}$ -dependent mechanism and the slowly inactivating component could result from a $Ca^{2＋}$ -dependent process. However, there should be signal transduction pathway which enhances inactivation no matter what the inactivation mechanism is. We have investigated the effect of phosphorylation on calcium channels of rat sympathetic neurons. Intracellular dialysis with the phosphatase inhibitors okadaic acid markedly enhanced the inactivation. The rapidly inactivating component is N-type calcium current, which is blocked by $\omega$-conotoxin GVIA. Staurosporine, a nonselective protein kinase inhibitor, prevented the action of okadaic acid, suggesting that protein phosphorylation is involved. More specifically lavendustin C, inhibitor of CaM kinase II, prevented the action of okadaic acid, suggesting that calmodulin dependent pathway is involved in inactivation process. It is not certain to this point whether phosphorylation process is inactivation itself. Molecular biological research regarding binding site should be followed to address the question of how the divalent cation binding site is related to phoshorylation process.

• Proceedings of the KAIS Fall Conference
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• 2011.05b
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• pp.854-857
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• 2011

육방정프레스 $420{\phi}$를 활용한 고온고압(high pressure high temperature: HPHT) 방법으로 금속촉매층 ($Ni_{77}Fe_{11}Mn_9Co_3$)과 카본디스크가 순차적으로 적층된 셀에 인산칼슘을 첨가함에 따라 합성다이아몬드 성장에 미치는 변화를 확인하였다. HPHT 공정의 압력, 온도, 시간을 각각 8 GPa, $1500^{\circ}C$, 280s로 고정하고, 카본과 금속촉매 층 사이에 인산칼슘을 각각 0, 0.08, 0.20, 0.28 mg씩 첨가하여 고온고압 합성을 수행하였다. 합성공정 후 적층셀의 중간부 셀 수직단면을 광학현미경과 마이크로 라만분광기로 분석하였다. 결과적으로 인산칼슘을 0.08 mg 도포하여 첨가하면 다이아몬드의 생성이 향상되었다. 반면 0.20 mg 이상에서는 도포되는 양이 증가 할수록 다이아몬드 생성이 억제되다가 0.28 mg 이상 첨가에서는 다이아몬드가 거의 생성되지 않는 특징을 보였다.

• Proceedings of the Materials Research Society of Korea Conference
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• 2010.05a
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• pp.5.2-5.2
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• 2010

인체 경조직인 뼈와 치아는 콜라겐 단백질과 인산칼슘 무기질 성분으로 구성된 최적의 복합체라 볼 수 있다. 이러한 인산칼슘 무기질 성분은 결정학적, 화학적으로 hydroxyapatite (HA, Ca10(PO4)6(OH)2)와 거의 유사하여 높은 생체활성과 골전도성을 보이는 것으로 알려져 있다. 또한, hydroxyapatite의 고온 분해 산물로 볼 수 있는 tricalcuim phosphate(TCP, Ca3(PO4)2)는 체내에 이식시 체액에 용해되어 신생골을 유도하는 생체흡수성 세라믹스로 알려져있다. 이러한 HA와 TCP는 우수한 생체친화성에도 불구하고 기계적 특성이 낮아, non-load bearing 부위에 적용이 되어 다공질의 골수복재 용도로 활용되거나, load-bearing부위의 적용을 위한 금속 implant 등의 생체친화성 보완을 위한 표면 코팅재로 사용되고 있는 실정이다. 본 발표에서는 생체특성이 매우 우수한 인산칼슘 생체세라믹스의 load-bearing part 적용을 위하여 강도 및 파괴인성의 기계적 특성을 증진시킨 사례를 살펴보고, non-load bearing part에 실제 사용되는 인산칼슘 생체세라믹스의 다공질(porous) 골수복재(bone graft)의 역학 특성 증진을 위한 아이디어와 함께, 역학 특성이 매우 뛰어난 지르코니아 생체세라믹스의 강화-소결법에 대하여 소개하고자 한다.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.30 no.4
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• pp.143-149
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• 2020

Calcium phosphates recognized as important bio-materials have been successfully synthesized by simple precipitation using waste abalone shells, which are rich mineral sources of calcium. Calcium hydroxide (Ca(OH)₂) originated from abalone shells was used as calcium source (precursor) for the preparation. Synthesis of calcium phosphates was performed by reacting calcium hydroxide with phosphoric acid (H₃PO₄) in aqueous solution. The initial precursor Ca/P ratios were adjusted to 1.50, 1.59 and 1.67, and the effect of the composition and the heat treatment on the synthesized powders and sintered bodies was investigated. The phases of the sintered ceramics prepared at 1150℃ were hydroxyapatite (HAp), β-tricalcium phosphate (β-TCP), and biphasic phosphate (HAp with β-TCP)), which were determined by the initial precursor Ca/P ratios. The results demonstrate the possibility for the synthesis of high value-added calcium phosphates from economical starting materials with low cost and high availability.

• Korean Journal of Materials Research
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• v.8 no.9
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• pp.865-870
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• 1998

The surfaces of titanium specimens were modified by immersion in calcium phosphate buffered solutions (pH 5.8, 7.0, 8.0) for 10 days and simulated body fluid(SBF) for 30 days by turns. The modified surfaces were characterized using scanning electron microscopy(SEM), X-ray diffractometery(XRD) and Fourier transform infrared spectrophotometer(FT-IR), and compared with specimen immersed in only SBF. The results indicated that the immersion in calcium phosphate buffered solutions accelerated the formation of the surface films. The formed layer showed granular shaped microstructure, and recognized as calcium phosphate such as a hydroxyapatite(HA) or a $\beta$-tri-calcium phosphate($\beta$-TCP). The thickness of the layer increased of the buffered solutions in order of pH 8.0, 7.0 and 5.8 and the density increased in order of pH 7.0, 8.0 and 5.8.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.11a
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• pp.42.2-42.2
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• 2009

인체의 치아 및 뼈는 무기질 성분과 단백질로 구성되어 있다. 생체세라믹스의 일종인 수산화아파타이트(Hydroxyapatite, HA; $Ca_{10}(PO_4)_6(OH)_2$)는 결정학적, 화학적으로뼈의 무기질 성분과 거의 유사하여 실제 체내에 들어가면 주위 뼈와 화학적 반응을 하여 단단한 결합을 이루는 생체활성(bioactive)을 가진 것으로 알려져 있다. 또한, 인산삼칼슘(Tri-Calcium Phosphate, TCP; $Ca_3(PO_4)_2$)은 체내에 이식 시 체액에 용해되어 신생골을 유도하는 생체흡수성(bioresorbable) 세라믹스로 알려져 있다. 상기 2종류를 포함한 인산칼슘계 화합물은 우수한 생체친화성에도 불구하고 역학 특성이 낮아, 하중을 거의 받지 않는 분야에만 사용되고 있는 실정이며, 하중을받는 분야(load-bearing part)에 적용하기 위해서는 고강도/고인성의 세라믹스와의 micro-composite이나 인산칼슘계화합물을 금속 표면에 코팅한 macro-composite의 형태로 사용되고 있다. 하중을 거의 받지 않는 분야, 예를 들어 치아 결손부를 보충할 dental shot과 같은 인산칼슘계 다공질 골충전재의 경우에도 취급 시 잘게 파손되는 문제점이 있어 치과의사들이 어려움을 호소하고 있는 실정이다. 본 연구에서는 HA, TCP의 역학특성을 증진시키고자 소결 공정 제어를 통하여 미세조직을 변화시켰으며, 미세조직 변화에 따른 세포반응성을 골포세포주를 이용하여 평가하였다.

• Journal of the Korea Institute of Building Construction
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• v.17 no.3
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• pp.253-260
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• 2017

As global warming became a worldwide issue, a significant effort has been made on the development of technology related to $CO_2$ capture and storage. Geologic sequestration of $CO_2$ is one of those technologies for safe disposal of $CO_2$. Geologic sequestration stores $CO_2$ in the form of supercritical fluid into the underground site surrounded by solid rock, and concrete is used for prevention of $CO_2$ leakage into the atmosphere. In such case, concrete may experience severe damage by attack of supercritical $CO_2$, and especially in contact with underground water, very aggressive form of carbonation can occur. In this work, to prevent such deterioration in concrete, calcium phosphates were added to the portland cement to produce hydroxyapatite, one of the most stable mineral in the world. Temperature rise, viscosity, set and stiffening, and strength development of cement paste incorporating three different types of calcium phosphates were investigated. According to the results, it was found that the addition of calcium phosphate increased apparent viscosity, but decreased maximum temperature rise and 28 day compressive strength. It was found that monocalcium phosphate was found to be inappropriate for portland cement based material. Applicability of dicalcium and tricalcium phosphates for portland cement needs to be evaluated with further investigation, including the long term compressive strength development.